The present invention relates generally to a fuel injection control system for controlling air-fuel mixture supply for a fuel injection internal combustion engine. More particularly, the invention relates to a fuel injection timing control for controlling the timing of injection of fuel into the engine, especially for the type of engine in which the fuel injection valve is disposed near an intake port and ejects atomized fuel towards an intake valve.
Generally, fuel injection takes place in synchronism with engine revolution. The timing of fuel injection is thus controlled in relation to the engine revolution with reference to the angular position of a crank shaft. A representative prior-art method of fuel injection is to direct the fuel injection valve towards the intake valve of each engine cylinder in order to inject the fuel towards the valve head of the intake valve. The fuel injected towards the valve head of the intake valve is atomized by colliding with the valve head and the ambient heat in the intake manifold. However, some of the fuel condenses on the valve head and is introduced into the engine combustion chamber in a liquid state. This causes cooling of the spark ignition plug and also results in inaccuracies and irregularities in the air/fuel ratio of the mixture. As a result, engine roughness is increased and/or engine starting characteristics are degraded.
The present invention is to resolve the abovementioned defects in the conventional fuel injection system for better engine performance.